The present invention relates to an apparatus for holding components of a type, e.g., mounting electronic components on electronic circuit boards, a component mounting apparatus with the component holding apparatus and a component mount method carried out by the component mounting apparatus.
A component sucking head part of a component mounting apparatus, which automatically mounts electronic components to an electronic circuit board, has a nozzle for sucking the electronic components and thereby mounting the component to the electronic circuit board. To precisely control touching of the nozzle and the electronic component at the time of the sucking and mounting is one factor in improving the quality of the electronic circuit board produced. An example of a conventional electronic component mounting apparatus will be described with reference to FIG. 14.
FIG. 14 shows a component sucking head part 101 comprising the nozzle, a suction device 103 for sucking the electronic component by the nozzle, an X-Y robot 102 for moving the head part 101 in X, Y directions and a control device 104 for controlling operations of the head part 101. The head part 101 is constructed as described hereinbelow. FIG. 14 shows only primary parts constituting the head part 101, and a body part of the head part 101, etc. are not illustrated in the drawing. A reference numeral 135 in FIG. 14 denotes a spline shaft, having a nozzle 136 set at one end part 135a for sucking an electronic component 138 through a suction operation and, a rotation receiver 143 provided at the other end part 135b.
The suction device 103 for carrying out the suction operation is connected to the other end part of the spline shaft via a suction tube 105. The air is sucked through the nozzle 136 and the spline shaft 135 to the suction device 103 by the suction operation of the suction device 103. A blow device 106 branches off the suction tube 105 and is connected to the other end part 135b of the spline shaft 135. The blow device 106 includes a valve for returning the interiors of the spline shaft 135 and nozzle 136 from a state in vacuum to a state of atmospheric pressure so as to free the electronic component 138 from the suction operation by the nozzle 136.
Two nuts 131, 134 are fitted to the spline shaft 135 to allow the spline shaft 135 to slide in the axial direction. These nuts 131, 134 are held to the body part (not shown) of the head part 101 via respective bearings 132, 133. The spline shaft 135 is accordingly movable in the axial direction relative to the body part and also rotatable about an axis of the spline 135.
The rotation about the axis of the line 135 is conducted by a motor 142. A pulley 139 is engaged with the spline shaft 135, which rotates along with the spline shaft 135. The spline shaft 135 is movable in the axial direction relative to the pulley 139. Meanwhile, a pulley 141 is connected to a driving shaft of the motor 142. The pulley 139 and pulley 141 are coupled by a belt 140. When the pulley 141 is rotated by the motor 142, the spline shaft 135 is related about the axis via the belt 140 and pulley 139.
The movement in the axial direction of the spline shaft 135 is achieved by a motor 149. More specifically, a nut 146 projecting a lever 147 is meshed with a ball screw 145 connected to a driving shaft of the motor 149 via a coupling 148. The lever 147 has, at its leading end, a roller 144 fitted in a groove 143a formed in the rotation receiver 143. Therefore, when the ball screw 145 is rotated by the motor 149, the lever 147 moves in the axial direction with the roller 144 engaged with the rotation receiver 143, thereby moving the spline shaft 135 in the axial direction.
The operation of the conventional component mounting apparatus in the above construction will be described with reference to FIG. 15.
At step (denoted by "S" in the drawing) 101, the X-Y robot 102 is moved by a control operation of the control device 104, thereby moving the head part 101 to a component suction position where the electronic component is to be sucked. At next step 102, the motor 149 is driven through the control of the control device 104 and, the spline shaft 135, namely, nozzle 136 is lowered. The suction device 103 is activated at step 103, and as a consequence the electronic component is sucked by the nozzle 136 at step 104. At step 105, the ball screw 145 is turned in reverse-rotation by the motor 149 to move the nozzle 136 up. Thereafter, the motor 142 is driven by the control of the control device 104 to rotate the nozzle 136 to a proper position so as to correctly position the sucked electronic component in a mount direction. At subsequent step 106, the X-Y robot is operated again to move the head part 101 to a component mount position on the electronic circuit board, and at step 107 the motor 149 is driven again to move the nozzle 136 down. Then at step 108 the electronic component 138 is mounted on the electronic circuit board while the blow device 106 is driven. After the mounting, the suction to the electronic component 138 is released, at step 109, and then the nozzle 136 is raised via the spline shaft 135.
Recently, high-speed operation is required for the mounting of the electronic component 138. However, in the above-described conventional component mounting apparatus, the blow device 106 is connected to the other end part 135b opposite to the one end part 135a of the spline shaft 135 where the nozzle 136 for sucking of the electronic component 138 is arranged. Therefore, it takes a long time for the interior of the nozzle 136 to return to atmospheric pressure state after the blow device 106 is activated to release the suction of the electronic component 138. In other words, the nozzle 136 stands still for a long time (a portion IV in FIG. 16) in a state while the electronic component 138 is mounted on the circuit board, thereby there is a disadvantage that the mounting time (a portion V in FIG. 16) required for mounting the electronic component 138 is increased. In the meantime, if the blow device 106 were started earlier during the descent of the nozzle 136 to shorten the above mount time, the nozzle 136 would be returned to the atmospheric pressure state before the electronic component 138 is completely mounted on the circuit board, thus causing the electronic component 138 to be blown away and mounted unstably.